Development of fabrication technologies for advanced tritium breeder pebbles by the sol–gel method

Highlights: • Li2TiO3 with excess Li (Li2+xTiO3+y) was developed as an advanced tritium breeder. • Pebble fabrication by the sol–gel method is a promising technique for the mass production of advanced tritium breeder pebbles. • To increase the density of the sintered Li2+xTiO3+y pebbles, the sintering temperature was changed. • At 1353 K, the density of the pebbles increased to approximately 85% T.D. without any increase in the grain size. -- Abstract: Demonstration power plant (DEMO) reactors require advanced tritium breeders with high thermal stability. Li2TiO3 with excess Li (Li2+xTiO3+y) was developed as an advanced tritium breeder. Pebble fabrication by the sol–gel method is a promising technique for the mass production of advanced tritium breeder pebbles. I have been developing a sol–gel technique for fabricating Li2+xTiO3+y pebbles, and the next step is to optimize the granulation conditions to reach the target value. In a previous study, the average grain size on the surfaces and cross sections of sintered Li2+xTiO3+y pebbles was large whereas the theoretical density (T.D.) of these pebbles was small. To increase the density of the sintered Li2+xTiO3+y pebbles, the sintering temperature was changed, and at 1353 K, the density of the pebbles increased to approximately 85% T.D. without any increase in the grain size. This suggests that the pore size in the sintered Li2+xTiO3+y pebbles decreased because of sintering in vacuum and argon